Question

The area of circle b is 25 times greater than the area of circle a. The radius of circle a is 3. What is the radius of circle a of circle b

Answer 1

Circle a: π×r1^2=π×3^2=π×9. r1=3
Circle b: π×r2^2
(π×9)×25=π×r2^2. ( 25 Times circle a equals one time circle b)
9×25=r2^2
r2=√9×25= √225=15